The present invention relates generally to a conveying apparatus, and more particularly to a conveying apparatus including an endless traction element.
A conveying apparatus is disclosed in Japanese Patent Application Publication No. 2007-314311. The conveying apparatus disclosed in the Publication includes a rotatable sprocket and a chain wound around the sprocket so as to move in an endless path and having a plurality of jigs on which work pieces are placed at predetermined intervals. In the conveying apparatus, if the diameter of the sprocket is reduced, interference occurs between any two adjacent jigs. Thus, the diameter of the sprocket is restricted by the size of the jig.
In order to solve this problem, a conveying apparatus having a chain with a reduced turning radius is disclosed in Japanese Examined Utility Model Publication No. 53-33985. In the conveying apparatus disclosed in this Publication, a chain is engaged with a chain wheel which is fixedly mounted on a shaft which is in turn rotatably supported by a bearing support. A plurality of guide cylinders is fixedly mounted to the chain through attachments at an equidistant interval or at an integral multiple interval and a support bar is vertically slidably inserted through each of the guide cylinder. Each support bar is fixedly mounted to a plate at the bottom and a roller is rotatably mounted to the support bar at the bottom thereof. A guide rail is fixedly mounted to the frame of the conveying apparatus. The guide rail extends curved vertically upward or downward from the starting point of the engagement between the chain and the chain wheel along the circumference of the chain wheel. Thus, the rollers travel on the guide rail with the movement of the chain.
According to the conveying apparatus disclosed in the Publication No. 53-33985, the rollers travel on the guide rail with the movement of the chain. Accordingly, the support bars and plates move upward and downward on the guide rail along the circumference of the chain wheel. When the chain is driven to move around the chain wheel, any two adjacent plates moving around the chain wheel overlap with each other as seen from the top of the plates. Because such two adjacent plates are positioned one above the other while moving around the chain wheel, no contact interference occurs between the plates.
In the conveying apparatus disclosed in the Publication No. 53-33985, even if the turning radius of the plate-shaped conveying table is reduced, the adjacent conveying tables moving around the chain wheel may be prevented from interfering with each other at the curved path of the conveying path. However, the conveying apparatus that allows the conveying tables to move vertically upward and downward becomes complicated in structure and requires a space allowing the vertical movement of the conveying tables. In addition, since a part of the upper conveying table overlaps the lower conveying table as seen from the top, there is a fear that an article placed on one table may interfere with an article on another conveying table.
The present invention is directed to providing a conveying apparatus which prevents any two adjacent conveying tables moving on a curved path from interfering with each other without positioning one table above or below its adjacent table when moving on the curved path, even if the turning radius of the curved path is reduced.